I have been trying to figure out if it is possible to create a matrix surround system in my car by wiring the rear speakers like in this diagram:



Has anyone ever tried to do this and will it work with an aftermarket car amplifier?

 

I tried that and did not get much sound output. I use the same trick with my Behringer EP1500 at home and it has enough drive to get the L-R output...although all depends on the program material and the mixdown the studio did with the recording.

 

I'm toying with the idea of hooking up an old Hughes SRS unit for the same effect only with more control. Alas, I'd need to use an inverter to power the unit.

 

Guys, you are going about this the wrong way.

What you are doing is only providing the rear/second set of speakers with more power. This is commonly used in installations (churches, etc) when you have three speakers - two near field, short throw & one far field long throw - that you want to power from a single two channel amplifier. This requires a mono signal to work, and the amplifier usually isi n bridged-mono mode (however this depends heavily on the design of the amplifier and SHOULD NOT be attempted if you are not sure if it will work or burn something up). The single far field speaker is connected to the two + terminals on the amplifier, hence giving it access to the amplifiers bridged output and therefore it shall be louder by approx. +3 db than the other two. The other two speakers are connected to the + and - terminals of their respective channels. This does not create any surround effects, only provides the single far field speaker to be louder to compensate for the distance it must throw. Like I said before, all you are doing is just powering the rear speakers with about 2X the power of the fronts (+3db). It really won't make that much of a difference at all. It could, however - burn up your amplifier. Two 4 ohm car speakers is a 2 ohm load to a bridged amp, which is the minimum load (e.g. the lowest you should go) for most amps. You are also adding another 4 ohm combined load to that, so your amp is seeing 1.33 ohms. So, unless your amp is 1 ohm stable, it will either turn off to protect itself, or burn up in a miserable death. Also, if you are feeding the amp a stereo signal, and the amp is not bridged to mono, hooking the rear speakers up as shown in your diagram will cause the two amp channels to fight each other, and eventually also burn up the amp.

The matrix surround effect you are looking for is just simple delays to create the feeling the signal is more than two channels of audio. A simple DSP chip can accomplish this easily, it shouldn't be hard to find a 12v device that can do it. If you are not looking for a surround effect, but more of a "spacial enhancer" to make it seem like your speakers are spread further apart, a similar DSP chip can accomlish this as well.

Oh, and lose that Behringer junk...Crown or QSC

-Michael

 

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I believe this is where this thread started from...
http://sound.westhost.com/project18.htm
SRS labs has a $10 device (click on shop at srs store) that I plan on trying. I'll report back with results. Ten+ years ago when the AK-100 came out it was amazing on my rudimentary "home theatre".

 

Show me which device you want to try? I can't seem to find the store on that site.

 

Try here...http://www.srs-store.com/store/mall/prod_wt.asp

 

I just ordered one too... for $10 you can't go wrong.

 

mcdanjw:

The SRS Labs "wow" unit is powered by a 18volt AC wall wart and has internal 78L12 and 79L12 regulators for a +/- 12 to common rail. I've externally hooked up a DC-DC converter (24pin DIP) that accepts 9-18vdc in and outputs the necessary +12, -12, common for the unit and it works fine...though you can't use the coaxial plug :-( Internal modifications are needed.
Another fly in the ointment is the stereo mini jacks for input/output have a common ground and the BOSE amp line inputs are balanced and NOT ground/common referenced. When I get four 1:1 audio isolation transformers in I'll hook it up in the CLS. More of a pain than I had expected, but a neat project to play with.